In a current wireless communication environment, with appearance and spread of various devices such as a smart phone and a tablet PC that require a machine-to-machine (M2M) communication and a large amount of data transmission, data requirements for a cellular network are very rapidly increasing.
In order to satisfy large data requirements, a communication technology is developed into a carrier aggregation technology and a cognitive radio technology for efficiently using more frequency bands and a multi-antenna technology and a multi-base station cooperative technology for increasing data capacity in a limited frequency. In addition, a communication environment evolves so that density of accessible nodes around a user is increased.
A system having the high density nodes may have higher system performance by cooperation among the nodes. Such a system has higher performance than that in which nodes operate as independent base stations (for example, a base station (BS), an advanced BS (ABS), a node B (NB), an eNode B (eNB), and an access point (AP)) that do not cooperate with each other.